Lynette Johns OD FAAO FSLS
As so eloquently described by Dr. Maria Walker in October’s I-Site case report, there is much to be investigated regarding the turbid clouding that can be a source of scleral lens dropout or a deterrent for scleral lens wear. In practice, without the ability to analyze the fluid and debris, we have encountered three types of debris. These three types can occur together in many cases, but depending on the type, we manage them in different ways.
We describe this debris as mucus (figure 1, image to the right); however, it has not been analyzed. Typically, it appears as white, fluffy, small debris that floats in the reservoir. In some extreme cases of larger debris, it can settle in the inferior reservoir with increased wearing time. When we observe this type of debris, we consider two situations. First, we will evert the eyelid and look for any signs of giant papillary conjunctivitis (GPC). Even in mild cases, if we see that the palpebral conjunctiva is injected, this may contribute to the debris effect. To manage this situation, we reduce wearing time, deep clean the lens with a sodium hypochlorite-potassium bromide-based system, and introduce an enzymatic cleaner to the care regimen. We also evaluate the fit of the scleral lens. If there is edge lift superiorly confirmed by fluorescein, the lens edge-eyelid interaction may be the source of the papillary reaction, and we reduce the edge lift either by tightening the peripheral curves or adding back-surface toricity. A second source of this debris may be from a reaction to preservative in the cleaning or soaking solution. The bulbar conjunctiva may be mildly injected; however, the reaction to the preservative is not significant enough to induce corneal staining. Eliminating the preservative can have a dramatic effect on reducing the particulate white reservoir debris.
Fogging associated with atopic disease
Some patients have both atopic disease and keratoconus; there is a known association between these conditions.1 We have observed a unique type of fogging under the lens in patients with atopy that appears as much-diluted milk (figure 2, on right). Efforts to reduce tear exchange by improving the alignment of the fitting with tighter peripheral curves or back-surface toricity are not always effective. In these patients, we introduce topical mast cell stabilizers, and in extreme cases, we add a topical steroid of low penetrance commonly referred to as a “soft steroid.” As a reminder, careful monitoring of patients using steroid and contact lenses is strongly advised.
The third and last type of debris we observed is an oil droplet form of debris (figure 3, on right). It looks like olive oil floating over water. It can be a yellowish color, and it is sometimes refractile in nature.
When we observe this type of debris, we carefully re-examine the eyelids for any signs of meibomian gland dysfunction (figure 4, on right) or blepharitis. Aggressively treating the lids can minimize this debris.
Also, reducing excessive tear exchange by manipulating the peripheral curves can be quite helpful in managing this debris.
Alternative management of debris in reservoir
In clinical practice, we found that the debris was often in the tear film and found its way under the scleral lens. As Dr. Walker mentioned in her case report, using a high-viscosity, preservative-free artificial tear can help prevent or reduce the inflow of debris into the reservoir.
When evaluating the scleral lens fit, paths of excessive tear exchange can be easily identified by adding fluorescein while the lens is worn (figure 5, on right). If the exchange is occurring around the periphery of the lens, steepening/tightening the peripheral curves is recommended. If one sector has significant exchange, it is helpful to observe the opposite sector along the same meridian. If excessive exchange is present, then back-surface toric peripheral curves can improve and reduce this path of debris. If these fitting changes do not effectively solve the problem, refitting the patient into a corneo-scleral lens significantly reduces debris because corneal contact essentially blocks the reservoir from excessive tear exchange. Movement is important when fitting corneo-scleral lenses, so tear exchange still occurs but is minimal compared to full scleral lenses. When fitting corneo-scleral lenses, carefully evaluate the cornea for any mechanical influences of the fit that induce staining or neovascularization.
Some patients with severe ocular surface disease complain of fogging immediately after the lens is applied. Removing and refreshing the solution can resolve the problem. In those patients, soaking their eyes with an eyecup to draw the surface debris out prior to lens application is quite helpful. Advise patients to clean and disinfect the eyecup after use.
Debris in the reservoir is a frustrating problem with scleral lenses for both the patient and the fitter. This reduces optimal visual acuity and creates significant glare and halos for the patient. Understanding that the debris may be associated with ocular conditions can help reduce the problem when medical management is introduced. Also, manipulating the fit by improving scleral landing zone alignment can block the path of the debris from entering the reservoir. Making every effort to reduce reservoir debris will minimize the risk for scleral lens dropout.
Lynette Johns is an adjunct assistant professor and clinical attending in contact lenses at the New England College of Optometry.
She was formerly the senior optometrist at the Boston Foundation for Sight where she exclusively fit scleral lenses and managed complex corneal disease.
She is a fellow of the American Academy of Optometry and Scleral Lens Education Society as well as a member of the BCLA. She is a clinical and educational consultant to the GP and specialty soft lens division of Bausch + Lomb.